1. The problem statement, all variables and given/known data I have a cylinder that's made up of three sections, brass, stainless steel, brass. There's a heat source at the top and a heat sink at the bottom. I know the overall heat transfer coefficient, power supplied to the heater, length, diameter, cross-sectional area of the cylinder. I also know the temperature of the heat sink, heat source and the average surface temperature. How do I go about it roughly? 2. Relevant equations q" = -k * (dT/dx) q = A * q" = (k/L) * A * (TL - TR) L/Keq = L1/k1 + L2/k2 + L3/k3 3. The attempt at a solution Can't figure it out.